Recording timer

ABSTRACT

A recording timer for illustrating characteristics of various types of motion with respect to time, comprising means movable at a constant rate for repetitively creating impressions on a movable media at intervals spaced according to the rate of movement of the media and variations thereof.

United States Patent [72] Inventor Charles 1. Lindsay Marlboro, Mass.

21 Appl. No. 8,201

[22] Filed Feb. 3, 1970 [45] Patented Oct. 5, 1971 [7 3] Assignee D. C. Heath and Company Lexington, Mass.

[54] RECORDING TIMER 6 Claims, 4 Drawing Figs.

[52] US. Cl 346/71, 346/106, 346/141 [51] Int. Cl Gold 9/22 50 Field of Search 346/71. 78, 105.106. 141

[56] References Cited UNITED STATES PATENTS 3,520,981 7/1970 Chambers Primary Examiner-Joseph W. Hartary Attorneys-Harold A. Murphy and Joseph D. Pannone ABSTRACT: A recording timer for illustrating characteristics of various types of motion with respect to time, comprising means movable at a constant rate for repetitively creating impressions on a movable media at intervals spaced according to the rate of movement of the media and variations thereof.

PATENTED 0m 5 19m INVENTOR CHARL l. LINDSAY AGENT RECORDING TIMER BACKGROUND OF THE INVENTION Various types of devices have been utilized for attempting to create records which visibly indicate the rate with respect to time at which a movable member is moving and the acceleration or deceleration thereof. For example, recording timers are useful in making a visible record to indicate the motion with respect to time of a falling object accelerating due to the force of gravity, or the rate at which a pendulum swings; they are also useful in visibly depicting motion with respect to time of a weight suspended on a spring, or a weight sliding or rolling down an incline. Such devices can be relatively complex.

However, simple recording timers are made which may be used as laboratory apparatus for use in places such as schools, where studies of time and motion are advantageously aided by simple pictorial or graphic illustrations. Known device utilized for this purpose embody a vibrating cantilever device for the marking mechanism and an ordinary low-voltage bell clapper.

Problems have been encountered with this type of device because the vibrating frequency is detennined by a set of mechanical points which make and break the circuit activating the motion of the bell clapper, and the vibrating frequency therefore is not constant. It has been found that the frequency also changes from one experiment to another because of handling, and because changes sometimes occur in the relative position of the unit with respect to the vertical force of gravity. Furthermore, two different units are not necessarily set to vibrate at the same frequency, and setting the frequency to a desired rate is nearly impossible.

A further problem encountered with a bell clapper mechanism of this sort is that when the recording media is moved at relatively high speeds the dwell time during which the striker makes its impact upon the recording media is relatively long, causing the media to be retarded in its motion through the timer. As a result, the impressions on the media appear as dashes or elongated marks as opposed to the desired distinct and sharply defined dots.

SUMMARY OF THE INVENTION The above and other disadvantages of prior art recording timers of the character referred to above are overcome in the present invention wherein there is employed a marking mechanism which is operable at a constant speed. This mechanism includes a suitable small motor which drives a flywheel, which is mounted directly on its operating shaft, at a constant speed. Adjustment in the rate at which the flywheel is rotated is accomplished by variations in voltage applied to the motor. Mounted below the rotating flywheel is a disc of carbon paper under which the recording media is positioned. For example, the recording media may be a strip of paper tape which is free to move in a direction perpendicular to the axis of the motor shaft. The carbon paper disc is held in place by a headed pin and therefore is adapted to be rotated about the pin during operation of the device. Carried by the rim of the flywheel is a short length of bead chain which functions as the impact member. As the flywheel rotates, centrifugal force urges the chain outward radially from the flywheel and the free end of the chain strikes the carbon paper disc upon each revolution of the flywheel. The impact point is transferred to the tape by the carbon paper as a clearly defined dot.

The head chain structure is such that upon impact the relative movement between the parts of the chain permits slight bounce to occur so that the impression made upon the paper tape recording media will be in the form of a sharply defined dot as opposed to an elongated mark such as a dash.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an isometric view illustrating a preferred embodiment of this invention;

FIG. 2 is an enlarged fragmentary view of one end of the device shown in FIG. 1;

FIG. 3 is an enlarged sectional view of a portion of the flywheel of the device of FIG. 1; and

FIG. 4 is a fragmentary top plan view of a portion of the device shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings wherein like characters of reference describe like parts throughout the several views, the device illustrated in FIG. 1 includes a supporting base 10 carrying on its upper surface a metal plate 12. Mounted on plate 12 near one end thereof is a bracket 14 having a number of upwardly extending spring fingers 16. Supported by bracket 14 and resiliently held therein by spring fingers 16 is a motor 18. Motor 18 may be any suitable low-voltage motor such as a 1.5 volt DC motor having an operating shaft 20 which extends parallel with the surface of plate 12. Operating shaft 20 extends outwardly from one end of the motor 18 and carries thereon a flywheel 22, the flywheel being fixedly connected to shaft 20 for rotation therewith as by a setscrew 24 (FIG. 2). The flywheel is of such diameter that its periphery or rim is spaced above the metal plate 12 at a predetermined distance, and mounted on the plate 12 beneath the flywheel 22 is a disc 26 of carbon paper which is disposed with its carbonized surface facing downwardly. A second disc 28 may be located beneath the carbon paper disc 26, if desired, to protect the adjacent surface of the carbon paper. The discs 26 and 28 are held in place by a headed pin 30 which extends through the discs and into one of a pair of openings 32 or 34 provided therefore in the metal plate 12.

The openings 32 and 34 also extend into ,the base 10 so that the pin can be properly supported. Selection of the particular opening 32 or 34 is in accordance with the particular direction of rotation of the flywheel, as will be apparent hereinafter.

A suitable recording media such as a paper tape 36 is disposed transversely across the surface of metal plate 12 and between the carbon paper disc 26 and its associated paper disc 28 as shown in FIG. 1. Means such as U-shaped guides 38 may be provided for properly locating the tape 36.

In accordance with the invention, it is desired that the motor 18 be operated to drive the flywheel 22 at a constant rate. In order to accomplish this, the motor is adapted to be connected to a suitable battery or other similar source of power by means of leads 40 and terminal clips 42. The flywheel 22 is provided in its rim or periphery with an opening 44 (FIG. 3) within which is located one end of a ball chain 46, more specifically one of the balls 48 of the chain. The ball 48 may be retained within opening 44 by any suitable means such as by peening the outer edge of the opening 44. The chain may be of suitable length whereby when the opening 44 is positioned directly above the carbon paper the chain will be slightly longer than the space between the flywheel and the carbon paper. This is indicated in FIG. 2.

When the flywheel rotates in response to operation of the motor, centrifugal force acts upon the bead chain 46 and urges the chain outward radially from the flywheel. Upon each revolution of the flywheel the free end of the bead chain strikes the carbon paper disc and the impact point is transferred by the carbonized surface to the tape 36 as a clearly defined dot. The structure of a conventional bead chain is such that the beads or balls 48 are somewhat loosely mounted upon the connecting chain portions so that when the end ball of the chain makes contact with the carbon paper disc, a bouncing thereof is pennitted so that the impact member will not dwell upon the carbon paper. Thus the dot impression will be sharply defined.

The rotational speed of the flywheel and the repetitive impacts of the ball chain upon the carbon paper disc introduce the time factor into this mechanism. The motion factor is introduced by moving the recording tape 36 lengthwise during a series of impacts. Any suitable desired mechanism capable of motion may be attached to one end of the tape 36 so as to cause the tape to move lengthwise. For example, a swinging pendulum can be attached to the tape and allowed to swing whereupon its swinging motion will draw the tape across plate 12 and the simultaneous rotation of the flywheel 22 will cause a series of spaced dots to appear on the tape, the spacings between the dots being controlled by the rate at which the pendulum moves the tape across the plate. It will be apparent that the dots will be closely spaced where movement of the pendulum is relatively slow, with the spacing being increased as the pendulum motion increases.

It will be apparent that the motor may be driven in one direction or in the reverse direction. Therefore, it is important that the carbon paper disc 26 be located with its center of revolution disposed at one side or the other of a vertical plane through the axis of the motor-operating shaft so that upon impact by ball chain 46 the carbon paper will be rotated slightly to constantly provide a fresh surface to the tape 36. This enables sharply defined dots to be constantly made by the device. For example, if the flywheel rotates in a counterclockwise direction as indicated by the arrow in FIG. 2, the carbon paper disc will be mounted on a pin 30 which is located in opening 32 (FIG. 4). Should the motor be operated in the reverse direction, the pin 30 will be located in opening 34.

It will be apparent from the foregoing that a device of the character described is a simple mechanism suitable for use in educational sciences as a laboratory apparatus and has applications in physics and earth sciences such as are presently being taught at secondary school levels.

A recording timer as disclosed herein is adapted to mark at a constant rate, which rate can be set to any frequency within specified limits by control of the input voltage. This timer design eliminates the problem of indistinct or elongated marks or impressions on the tape by virtue of the extremely short duration of the actual marking action. The motor turns at approximately 2,600 revolutions per minute at l.5-volts DC input. At this speed, the angular velocity of the end of the bead chain which impacts the carbon disc is approximately 15 ft./second.

In one modification of this invention, there is utilized a tape which inherently embodies its own marking means. For example, such a tape when impacted as described by ball chain device 46 will convert the point of impact into a visible impression without the interposition of separate carbon disc 26 as disclosed in the first embodiment. One type of such tape comprises a layer of a specific color which is covered by an opaque waxlike coating, the coating being easily removed by the impact device so that the colored layer will become visible through the small openings in the coating where the coating received the impacts.

From the foregoing it will be apparent that all of the objectives have been achieved by the recording timer described herein. It will be apparent that various modifications may be made in the structure shown and described without departing from the spirit of the invention. Therefore, all matter shown and described is to be interpreted as illustrative and not in a limiting sense.

lclaim:

l. A recording timer comprising:

a base,

means for movably supporting recording media on said base,

and means for producing a series of repetitive impacts upon said recording media when positioned on the base whereby the recording media will produce visible impressions corresponding to said impacts, said impact means when operated being such as continuously produces impacts of constant frequency in any position of use,

said means for producing impacts comprising an electric motor, a flywheel operably connected to and rotatable by said motor, and impact means carried by said flywheel for engaging said recording media upon each revolution of the flywheel,

said impact means comprising a device embodying a number of loosely interconnected elements in a chainlike configuration for extension radially outward from the periphery of the flywheel when subjected to centrifugal force upon rotation of the flywheel and for engagement by the outermost element with the recording media upon each revolution of the flywheel.

2. A recording timer as set forth in claim 1 wherein said outermost element is connected to the adjoining element by connecting means for permitting retraction of the outermost element away from the recording media immediately after initial impact of the element with the recording media.

3. A recording timer as set forth in claim 1 wherein said impact means comprises a section of bead chain, one

end of which is fixed to the periphery of the flywheel.

4. A recording timer comprising a base,

means for movably supporting recording media on said base,

and means for producing a series of repetitive impacts upon said recording media when positioned on the base whereby the recording media will produce visible impressions corresponding to said impacts, said impact means when operated being such as continuously produces impacts of constant frequency in any position of use,

said means for producing impacts comprising an electric motor, a flywheel operably connected to and rotatable by said motor, and impact means carried by said flywheel for engaging said recording media upon each revolution of the flywheel,

and said recording media comprising a disc of carbon paper located with a portion thereof disposed directly beneath the flywheel,

said base being provided with two spaced apertures at locations respectively on opposite sides of a vertical plane extending through the axis of the flywheel,

and pinlike means penetrating the carbon paper and selectively located in a predetermined one of the apertures depending upon the direction of rotation of the flywheel and about which said paper rotates.

5. A recording timer comprising:

a base,

a motor support bracket fixed to said base,

a motor mounted in the bracket,

means for connecting the motor to a source of electrical energy,

a flywheel operatively connected to the motor for rotation thereby, marking means disposed on said base beneath the flywheel, means for movably supporting a tapelike recording media beneath the portion of the marking means which lies beneath the flywheel,

and impact means carried by the flywheel for impact with the marking means upon each revolution of the flywheel and for consequently causing said means to produce a visible impression of each such impact upon the recording media, with the spacings between adjacent impressions being spaced in accordance with the rate of rotation of the flywheel and the rate of movement of the recording media,

said marking means being a disc of carbon paper mounted for rotary movement about its center when engaged by said impact means.

6. A recording timer as set forth in claim 5 wherein said base is provided with two spaced apertures at locations respectively on opposite sides of a vertical plane extending through the axis of the flywheel,

and pinlike means penetrates the carbon paper and is selectively located in a predetermined one of the apertures depending upon the direction of rotation of the flywheel and about which said paper is rotatable. 

1. A recorDing timer comprising: a base, means for movably supporting recording media on said base, and means for producing a series of repetitive impacts upon said recording media when positioned on the base whereby the recording media will produce visible impressions corresponding to said impacts, said impact means when operated being such as continuously produces impacts of constant frequency in any position of use, said means for producing impacts comprising an electric motor, a flywheel operably connected to and rotatable by said motor, and impact means carried by said flywheel for engaging said recording media upon each revolution of the flywheel, said impact means comprising a device embodying a number of loosely interconnected elements in a chainlike configuration for extension radially outward from the periphery of the flywheel when subjected to centrifugal force upon rotation of the flywheel and for engagement by the outermost element with the recording media upon each revolution of the flywheel.
 2. A recording timer as set forth in claim 1 wherein said outermost element is connected to the adjoining element by connecting means for permitting retraction of the outermost element away from the recording media immediately after initial impact of the element with the recording media.
 3. A recording timer as set forth in claim 1 wherein said impact means comprises a section of bead chain, one end of which is fixed to the periphery of the flywheel.
 4. A recording timer comprising a base, means for movably supporting recording media on said base, and means for producing a series of repetitive impacts upon said recording media when positioned on the base whereby the recording media will produce visible impressions corresponding to said impacts, said impact means when operated being such as continuously produces impacts of constant frequency in any position of use, said means for producing impacts comprising an electric motor, a flywheel operably connected to and rotatable by said motor, and impact means carried by said flywheel for engaging said recording media upon each revolution of the flywheel, and said recording media comprising a disc of carbon paper located with a portion thereof disposed directly beneath the flywheel, said base being provided with two spaced apertures at locations respectively on opposite sides of a vertical plane extending through the axis of the flywheel, and pinlike means penetrating the carbon paper and selectively located in a predetermined one of the apertures depending upon the direction of rotation of the flywheel and about which said paper rotates.
 5. A recording timer comprising: a base, a motor support bracket fixed to said base, a motor mounted in the bracket, means for connecting the motor to a source of electrical energy, a flywheel operatively connected to the motor for rotation thereby, marking means disposed on said base beneath the flywheel, means for movably supporting a tapelike recording media beneath the portion of the marking means which lies beneath the flywheel, and impact means carried by the flywheel for impact with the marking means upon each revolution of the flywheel and for consequently causing said means to produce a visible impression of each such impact upon the recording media, with the spacings between adjacent impressions being spaced in accordance with the rate of rotation of the flywheel and the rate of movement of the recording media, said marking means being a disc of carbon paper mounted for rotary movement about its center when engaged by said impact means.
 6. A recording timer as set forth in claim 5 wherein said base is provided with two spaced apertures at locations respectively on opposite sides of a vertical plane extending through the axis of the flywheel, and pinlike means penetrates the carbon paper and is selectively located in a predetermined one of the apertures depending upon tHe direction of rotation of the flywheel and about which said paper is rotatable. 